L. C. P. M. de Smet

Delft University of Technology, Delft, South Holland, Netherlands

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Publications (11)18.49 Total impact

  • M. Amirilargani · M. Sadrzadeh · E.J.R. Sudhölter · L.C.P.M. de Smet
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    ABSTRACT: Organic solvent nanofiltration (OSN) is an emerging technology in which membranes are used for organic solvent separation and purifications. It’s fields of applications range from pharmacy, catalyst regeneration, to oil and solvent treatments. A major challenge is to maintain a high stability of these (modified) membranes under different feed conditions. Tailoring the selective layer of OSN membranes is the main approach to develop functionalized membranes which show stable high selectivities and permeabilities. During the past decade, methods such as grafting, light-induced modification, plasma treatment, and polyelectrolyte modification have been intensively studied. This paper reviews the recent progress in this field of surface modification of different types of polymeric and also of ceramic OSN membranes. First, the most crucial surface layer properties that affect the OSN membranes properties are described in detail. Next, different surface modification methods and their effects on membrane selectivity and permeability are reviewed and compared. Finally, a perspective is given on expected future trends in this highly challenging and important field of current research.
    No preview · Article · Dec 2015
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    ABSTRACT: Capacitive detection of organic pollutants present in water at low ppm and ppb levels by means of polymer-coated interdigitated electrode (IDE) structures is a challenging research and engineering task. The detection limit of a measuring system is dependent on its noise level and systematic physical nonidealties. To achieve a high detection sensitivity all parasitic impedance effects must be reduced as much as possible in order not to interfere with the information carrying signal. In comparison to 'closed', three-dimensional structures, the electrical sensing field of the 'open', planar IDE structure is geometrically difficult to guard. Direct exposure to aqueous solutions may cause unpredictable parasitic coupling to the surrounding, which results in changes in the sensitivity of response of the device to changes in environmental conditions such as salt concentration and pH. Thicker polymer layers increase the distance between the electrode plane and the water phase, thereby reducing the parasitic coupling effects but at significant cost of the sensing response time. In this work we demonstrate how water-enhanced electrical coupling to guarding electrodes is a key mechanism in achieving response immunity to parasitic electric-field bending without impairing the detection performance of the polymer-coated IDE platform. Our work contributes to the knowledge of capacitive response interpretation and mechanisms and points out important design considerations for improved sensing systems, in particular for applications in aqueous environments such as droplet and flow detectors for biomedical and environmental fields.
    No preview · Article · Oct 2015 · Sensors and Actuators A Physical
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    ABSTRACT: Nanocrystalline diamond (NCD) is a promising material for electronic and mechanical micro- and nanodevices. Here we introduce a versatile pick-up and drop technique that makes it possible to investigate the electrical, optical and mechanical properties of as-grown NCD films. Using this technique, NCD nanosheets, as thin as 55 nm, can be picked-up from a growth substrate and positioned on another substrate. As a proof of concept, electronic devices and mechanical resonators are fabricated and their properties are characterized. In addition, the versatility of the method is further explored by transferring NCD nanosheets onto an optical fibre, which allows measuring its optical absorption. Finally, we show that NCD nanosheets can also be transferred onto 2D crystals, such as MoS2, to fabricate heterostructures. Pick-up and drop transfer enables the fabrication of a variety of NCD-based devices without requiring lithography or wet processing.
    Full-text · Article · Mar 2015 · Nanotechnology
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    ABSTRACT: A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ∼50 ml∕min (STP) at ∼850 °C. The films were extensively evaluated by surface wettability, electron affinity, elemental composition, photoconductivity, and redox studies. In addition, electrografting experiments were performed. The surface characteristics as well as the optoelectronic and redox properties of the annealed films were found to be very similar to hydrogen plasma-treated films. Moreover, the presented method is compatible with atmospheric pressure and provides a low-cost solution to hydrogenate CVD diamond, which makes it interesting for industrial applications. The plausible mechanism for the hydrogen termination of CVD diamond films is based on the formation of surface carbon dangling bonds and carbon-carbon unsaturated bonds at the applied tempera-ture, which react with molecular hydrogen to produce a hydrogen-terminated surface.
    No preview · Article · Jun 2013 · The Journal of Chemical Physics
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    ABSTRACT: A high signal-to-noise ratio (SNR) in silicon nanowire (SiNW) field effect transistors (FETs) is crucial for detecting low concentrations of biological material as the signal changes are often small and difficult to be differentiated from the baseline signal. This reported work studies the low-frequency noise (1/f) as in Hooge's constant, αH, and the device detection limit of the SiNW FETs to evaluate the influence of the etching process used to define the nanowires (NWs). Two etching methods are compared: plane-dependent etching using potassium borate in water and reactive ion etching in Cl-based chemistry. All investigated devices have similar dopant type, doping concentration and dimensions, and were fabricated with the same process flow with the exception of the NW definition. The extracted average Hooge's constant for wet etching is found to be at least an order of magnitude lower (αH, avg = 7.96 × 10-4) compared with dry plasma-etched devices (αH, avg = 4.1 × 10-2), indicating a lower surface roughness and/or a lower amount of surface defects. This study shows that the newly developed method improves the electrical properties of the device, making it an interesting alternative to standard approaches used for fabrication of SiNW FETs as (bio)sensors.
    No preview · Article · Jun 2013 · Electronics Letters
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    ABSTRACT: A high-current annealing technique is used to fabricate nanogaps and hybrid diamond/graphite structures in boron-doped nanocrystalline diamond films. Nanometer-sized gaps down to 1 nm are produced using a feedback-controlled current annealing procedure. The nanogaps are characterized using scanning electron microscopy and electronic transport measurements. The structural changes produced by the elevated temperature, achieved by Joule heating during current annealing, are characterized using Raman spectroscopy. The formation of hybridized diamond/graphite structure is observed at the point of maximum heat accumulation.
    Full-text · Article · Dec 2012 · Applied Physics Letters
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    ABSTRACT: Silicon nanowire FET arrays have been designed and fabricated with a relatively low-cost, but wafer-scale process without the use of e-beam lithography. An optimized fabrication process that improves the etching uniformity of NWs and also provides a better control of the NW dimensions is presented. The fabricated devices are electrically characterized and their performance is discussed. A dedicated measurement set-up and a preparation procedure to employ these SiNW FET arrays for real time monitoring of the substance P activation of neurokinin (NK1) receptors in HEK 293 cells are presented.
    Full-text · Article · Jan 2012 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
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    ABSTRACT: This paper presents a method for using nanowire field-effect transistors (NW-FETs) as sensors in aqueous solutions without the need for a reference electrode. A pulsed-gate potential method is used to reduce instabilities related to the dynamics of ions and other charged species present in the solution. Application of this method results in a significant increase in the stability of the electrical properties of the devices, enabling reproducible characterization of aqueous media with NW-FETs. We show that this method can be applied to perform pH measurements with a silicon NW-FET.
    No preview · Article · Aug 2011 · IEEE Transactions on Electron Devices
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    ABSTRACT: We report on a relatively simple and cost-effective method for fabrication of Silicon Nanowire Field-Effect Transistor (SiNW FET) arrays with three {100} surfaces via IC–compatible, top-down processes. Devices fabricated with this process offers an extra advantage compared to other top down fabrication techniques by not just only offering one or two, but instead three well-defined surfaces. The method offers a precise control of the NWs width (down to sub-100nm) without the need for nanolithography. In addition, very smooth and straight sidewalls are obtained. The process flow requires just one mask step and room–temperature, wet etching for the nanowire patterning and is thus suitable for wafer-scale fabrication of nanowires arrays. Device characterization includes electrical characterization and pH measurements were performed using the fabricated SiNW FET arrays.
    No preview · Article · Jun 2011
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    ABSTRACT: The focus of this study is on incorporating pendant sulfonate groups along the backbone of a liquid crystalline polyester (LCPE) with the aim to improve the dispersion of single wall carbon nanotubes (SWNTs) and nanodiamonds (NDs). Two LCPE matrices, one sulfonated (LCPE-S) and one nonsulfonated reference polymer (LCPE-R), were successfully synthesized via a melt condensation method using aromatic and aliphatic AB, AA, and BB-type monomers. Upon the introduction of SWNT and ND particles, the glass transition temperature (T-g) of the sulfonated LCPE increased from 21.5 degrees C to 41.0 degrees C and 41.9 degrees C, for SWNTs and NDs, respectively. When sulfonate groups were absent, a decrease in T-g was observed. The storage modulus (E') followed a similar trend, i.e., E' increased from 1.3 GPa to 5.2 GPa and 3.4 GPa, upon the addition of NDs and SWNTs. The LCPE-S showed a lower thermal stability due to the loss of sulfonate groups, i.e. the 5% weight loss temperature (T-d(5%)) is similar to 280 degrees C for LCPE-S vs. 333 degrees C for LCPE-R. The decomposition temperature increased somewhat upon addition of the nanoparticles. The ability of dispersing carbon-based nanostructures combined with an accessible melt processing window makes sulfonated LCPs attractive matrices towards preparing nanocomposites with improved thermal and mechanical properties. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 1079-1087, 2011
    No preview · Article · Jan 2011 · Journal of Polymer Science Part A Polymer Chemistry
  • A.A. Martens · M. Bus · E.J.R. Sudhölter · L.C.P.M. de Smet

    No preview · Article · Nov 2010